Transmission with integrated drum gear brake
A transmission having an integrated gear and brake mechanism is disposed in a housing, the transmission having a variable drive mechanism, gear train, and an output axle engaged to the gear train. The output axle is driven by a final drive gear having an integrated drum brake within its circumference.
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This application is a divisional of U.S. patent application Ser. No. 13/490,727, filed on Jun. 7, 2012, which claims the benefit of Provisional Application No. 61/494,167, filed Jun. 7, 2011, the contents of all of which are incorporated herein by reference.
BACKGROUND OF THE INVENTIONThis application relates to a transmission having an integrated gear and brake mechanism that is useful in the drive systems of vehicles or utility transports.
SUMMARY OF THE INVENTIONA transmission having an integrated gear and brake mechanism, e.g. the transaxle of a vehicle, is disclosed herein. The integrated gear and brake mechanism provides a compact assembly with improved braking capacity, wherein the brake can be included in a common housing with the transmission. Typically, a small utility vehicle equipped with a hydrostatic transmission or transaxle, such as a lawn tractor, relies on the inherent braking associated with the vehicle's engine and transmission combination when the transmission is returned to neutral. This braking effect requires drive belt integrity between the engine and transmission, a sufficient volume of hydraulic fluid in the hydraulic circuit between the transmission's pump and motor, and gear train integrity between the hydraulic motor and axle. On flat ground, these vehicles will be brought to a stop within a few feet without application of a dynamic brake. Consequently, many such vehicles are equipped with only a static parking brake designed for engagement with the motor shaft or a shaft disposed between the motor shaft and output axle. In other instances, a parking brake may directly engage the cylinder block of an axial piston hydraulic motor.
On sufficient inclines, however, gravity may overcome the vehicle's inherent braking effect permitting the vehicle to slowly move downhill when in neutral. Whether in neutral or not, failure of a drive train component, can result in the vehicle freewheeling down an incline. There is a need for a compact braking mechanism associated with the output axle. When used in a hydrostatic transaxle, the brake of the present invention is effective even if there is a loss of drive force applied to the axle caused by, for example, breakage of gear teeth in the drive train, loss of fluid integrity of the hydraulic circuit, or breakage of an input drive belt. The mechanical brake mechanism disclosed herein acts upon and within the final drive gear engaged to the output axle. The present invention has application to vehicles such as lawn mowers and tractors, garden tractors, snow throwers, and other applications where a compact drive unit is desired.
A better understanding of the objects, advantages, features, properties and relationships of the invention will be obtained from the following detailed description and accompanying drawings.
Main housing 21 is fastened to side housing 22 to form a sump in which the integrated hydrostatic transmission 25, gear train 35, and integrated gear and brake mechanism 30 are disposed. As will be understood from the aforementioned patents, hydrostatic transmission 25 transfers rotational force received from a prime mover, such as prime mover 91 in
The internal workings of integrated gear and brake mechanism 30 can be seen in
As shown in
The brake portion of the integrated gear and brake mechanism 30 is shown in
An optional parking brake may be added to transaxle 20L as depicted in
The transaxle 20L depicted herein is preferably used in tandem in connection with a zero turn vehicle.
While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any equivalent thereof.
Claims
1. An integrated gear and brake mechanism for an axle of a drive unit, said integrated gear and brake mechanism comprising:
- a housing defining an internal sump and rotatably supporting the axle, a first end of the axle being disposed in the sump and a second end of the axle extending from the housing;
- a gear entirely disposed in the sump and drivingly engaged to the axle;
- a brake surface formed on an internal circumference of the gear;
- a first brake shoe and a second brake shoe, each brake shoe having a brake pad in proximity to the brake surface of the gear;
- a fastener disposed in the sump, anchored to the housing, and pivotably engaged with the first brake shoe and with the second brake shoe;
- a brake actuation shaft rotatably supported by the housing, a first end of the brake actuation shaft being disposed in the sump and a second end of the brake actuation shaft extending from the housing; and
- a cam in contact with the brake actuation shaft and with a first end of each brake shoe, whereby the cam is capable of causing a radial motion of both brake shoes upon rotation of the brake actuation shaft.
2. The integrated gear and brake mechanism of claim 1, wherein a second end of the first brake shoe is anchored to a second end of the second brake shoe by the fastener.
3. The integrated gear and brake mechanism of claim 2, wherein the second end of the first brake shoe and the second end of the second brake shoe each comprise an opening through which the fastener passes.
4. The integrated gear and brake mechanism of claim 1, further comprising a spring engaged to each of the first and second brake shoes, wherein the spring is biased to maintain the first and second brake shoes away from the brake surface.
5. The integrated gear and brake mechanism of claim 1, wherein a rotational axis of the brake actuation shaft is parallel to a rotational axis of the axle.
6. The integrated gear and brake mechanism of claim 5, wherein the rotational axis of the brake actuation shaft is positioned internal to the circumference of the brake surface of the gear.
7. The integrated gear and brake mechanism of claim 1, wherein the axle is directly engaged to the gear through a gear hub on the gear.
8. An integrated gear and brake mechanism for an axle of a drive unit, said integrated gear and brake mechanism comprising:
- a side housing rotatably supporting a first end of the axle;
- a main housing fastened to the side housing to form a sump and rotatably supporting the axle, the axle extending through the main housing;
- a gear entirely disposed in the sump and including an internal circumference and a brake surface formed thereon;
- one or more brake shoes, each of the one or more brake shoes including a brake pad proximate the brake surface of the gear; and
- a fastener disposed in the sump, anchored to the main housing, and pivotably engaged with the one or more brake shoes;
- a cam contacting each of the one or more brake shoes such that movement of the cam causes each of the one or more brake shoes to engage the brake surface; and
- a rotatable brake actuation shaft extending through and supported by the main housing and engaged to and capable of causing movement of the cam.
9. The integrated gear and brake mechanism of claim 8, wherein the one or more brake shoes include a first brake shoe and a second brake shoe.
10. The integrated gear and brake mechanism of claim 9, wherein an end of the first brake shoe is anchored to an end of the second brake shoe by the fastener.
11. The integrated gear and brake mechanism of claim 10, wherein the end of the first brake shoe and the end of the second brake shoe each define an opening therethrough through which the fastener passes, and wherein the first brake shoe and the second brake shoe are configured to pivot about the fastener.
12. The integrated gear and brake mechanism of claim 8, wherein a rotational axis of the brake actuation shaft is parallel to a rotational axis of the axle.
13. The integrated gear and brake mechanism of claim 12, wherein the rotational axis of the brake actuation shaft is positioned radially inward of a circumference of the brake surface of the gear.
14. The integrated gear and brake mechanism of claim 12, wherein the cam is integrally formed with the brake actuation shaft.
15. The integrated gear and brake mechanism of claim 8, further comprising a spring connected to each of the one or more brake shoes, the spring biasing each of the one or more brake shoes away from the brake surface.
16. An integrated gear and brake mechanism comprising:
- a housing defining a sump;
- a gear train disposed in the sump and comprising a first gear and a second gear driven by the first gear, the second gear comprising an inner braking surface;
- an axle rotatably supported by the housing and engaged with the second gear, the second gear to provide a torque to the axle;
- a first brake shoe disposed in the second gear;
- a fastener disposed in the sump, anchored to the housing, and pivotably engaged with the first brake shoe;
- a cam slidably engaged with the first brake shoe to selectively push the first brake shoe toward the inner braking surface; and
- a brake actuation shaft rotatably supported by the housing and engaged with the cam.
17. The integrated gear and brake mechanism of claim 16, wherein a rotational axis of the brake actuation shaft is parallel to a rotational axis of the axle.
18. The integrated gear and brake mechanism of claim 17, wherein the rotational axis of the brake actuation shaft is positioned internal to the inner braking surface.
19. The integrated gear and brake mechanism of claim 16, further comprising a second brake shoe disposed in the second gear, wherein a second end of the first brake shoe is anchored to a second end of the second brake shoe by the fastener.
20. The integrated gear and brake mechanism of claim 16, wherein a second end of the first brake shoe comprises an opening through which the fastener passes.
21. The integrated gear and brake mechanism of claim 16, further comprising a spring engaged to the first brake shoe to urge the first brake shoe away from the inner braking surface.
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Type: Grant
Filed: Dec 29, 2014
Date of Patent: Nov 14, 2017
Assignee: Hydro-Gear Limited Partnership (Sullivan, IL)
Inventors: Michael L. Bennett (Sullivan, IL), Nathan W. Bonny (Shelbyville, IL)
Primary Examiner: Christopher Schwartz
Application Number: 14/584,144
International Classification: F16D 51/00 (20060101); F16H 63/34 (20060101); F16D 51/22 (20060101); B60T 1/06 (20060101);